1. Field of the Invention
The invention relates to a brake control system that controls braking force applied to a wheel provided on a vehicle and a control method for the brake control system.
2. Description of the Related Art
Japanese Patent Application Publication No. JP-A-11-180294, for example, describes a brake hydraulic pressure control system that is provided with a regulator which is connected in series downstream of an accumulator, and a pair of linear control valves, one for increasing pressure and one for decreasing pressure, which supply and discharge brake fluid of the regulator to and from wheel cylinders of four wheels. In this system the pressure increase linear control valve and the pressure decrease linear control valve are both used for the wheel cylinders of all four wheels which enables the number of linear valves to be reduced compared to when the hydraulic pressure is controlled using separate linear control valves provided for each wheel cylinder. From the viewpoint of cost reduction of the system, therefore, using a pair of common linear control valves, i.e., the pressure increase linear control valve and the pressure decrease linear control valve, is advantageous.
In the system described above, the pair of pressure increase and pressure decrease linear control valves control the hydraulic pressure from a power hydraulic pressure source such as an accumulator so that equal hydraulic pressure is introduced into the wheel cylinders of all four wheels. However, from the viewpoint of improving vehicle stability or failsafe ability, for example, it may be desirable to vary the hydraulic pressures introduced from the power hydraulic pressure source into the wheel cylinders so that they are not all equal.